1. Field of the Invention
The present invention relates to loading image textures for an animation, and in particular to pre-loading textures for animations that are to be performed in real time.
2. Description of the Related Art
The use of subtitles in everyday television broadcasts has become widely accepted. As digital methods have become increasingly inexpensive and fast, subtitling has expanded into a wide range of animated graphics that can be used to accompany a broadcast. These animations may be of sufficient complexity that they must be prepared in an off-line environment before being committed to an on-air broadcast. However, many such broadcasts have unpredictable cue points in time, and as such are unsuitable for use with pre-prepared material of this kind. In order to maximise the impact and inter-activity of the images in a live broadcast, it is necessary to generate animations interactively in real time; effectively a performance of the cameras, talent and the production team all working together. Cues are then supplied to the animation system to initiate an animation sequence, or a scene.
While the amount of processing power currently available is considerable, general purpose computing platforms have not been specifically designed for real time image processing. In particular, the amount of data that is transferred during routine data processing operations can interfere with time critical tasks, such as the completion of rendering of the next frame during a live broadcast. Efficient moving of data requires the use of hardware methods of direct memory access (DMA) which are difficult to interrupt. Use of highly efficient DMA transfers is necessary because of the volume of data involved in image processing. However, unrestricted use of DMA prevents the system from operating in real time. Using slower non-DMA methods also restricts real time operation, because the rate of data transfer is then reduced.
Restricting the amount of data that can be moved about during real time operation can interfere significantly with the capabilities of the system, and also has the disadvantage that the users of such restricted systems must be made aware of highly technical issues, issues that will interfere with the creative act of designing an animated scene for a television broadcast.